Electrical coil



Dec. 23, 1941.

c. w. VERRIL L ELECTRICAL COIL Original Filed Jan. 15, 1939 wmvrm C. WVffi/P/ZL 2% v Aime/v0" Patented Dec. 23, 1941 ELECTRICAL COIL CharlesW. Verrill, Hinsdale, Ill., assignor to Western Electric Company,Incorporated, New

York, N. Y.,

a corporation of New York Original application January 13, 1939, SerialNo.

Divided and t his application August 17, 1940, Serial No. 353,081

7 Claims.

This invention relates to electrical coils and more particularly tospool wound electrical coils, and is a division of my earlier rial No.250,761, filed January 13, 1939, and now Patent No. 2,216,464, datedOctober 1, 1940.

In the manufacture of spool wound electrical coils, particularly ofenamel insulated wire, it is the practice, in some instances, to connecta bare lead wire to a bare end of enamel insulated wire preliminary tostarting the winding of the coil. The portion of the lead wire extendingfrom the inner face of an insulating washer at the spool head to thebare end of the insulated wire is covered with an insulating element toprevent the adjacent layers of enameled winding wire from working orbeing pressed downwardly along the inner face of the washer into contactwiththe bare lead wire, which condition may result in portions of theenamel becoming removed from the winding wire, thus short circuiting oneor more layers of the coil. One insulating element heretofore used hasbeen made from celanese silk treated to stiffen and improve itsinsulating qualities. Such material is not only expensive in its firstcost, but it requires subsequent treating, and due to its nature, evenafter treatment, is difilcuit to handle and thus a high degree of careand skill is required to apply it in the winding of the coil,

An object of this invention is to provide an electrical coil of theabove described type having improved means for insulating theuninsulated lead wire from the winding wire.

In order to attain this object, in accordance with the features of oneembodiment of the invention, as applied to spool wound electrical coils,an initially flat insulator is provided which is formed from celluloseacetate strip material folded adjacent one longitudinal edge to providea double flat fold which is appreciably spaced from the opposite edge ofthe sheet, the several thicknesses of material being coalesced byapplying colored acetone to a series of perforations formed in thefolded material and extending along the length of the fold, the coloredacetone seeping between the folds, coalescing the several thicknesses ofmaterial and producing a colored line. The single thickness of materialextending from one edge of the fold to the adiacent edge of the sheet isserrated to permit it to readily flex and form an outwardly directedflange at the annular corner or juncture of the inner face of the coilhead washer and a core of the coil while the single thickness ofmaterial extending from the opposite edge of the application, Se

fold to the other edge of the sheet is wrapped around the connected endsof the lead and winding wires. The fold adjacent the serrated edgeserves as a reinforcement and stiffener for the insulator which iseffective to prevent the single thickness of thin cellulose acetatematerial from tearing through the fold and also to facilitate thehandling of the insulator. In applying the insulator in the winding of acoil the colored line indicates to the operator which edge of theinsulator is serrated and thus facilitates the application thereof tothe coil. The fold is applied at the annular comer and thus the severalthicknesses of material provide increased insulation thereat.

A complete understanding of the invention may be had from the followingdetailed description taken in conjunction with the appended drawing, inwhich -Fig. 1 is an elevational view of a completed electrical coilembodying the invention;

Fig. 2 is an enlarged longitudinal vertical sectional view of the leftend of the coil shown in Fig. 1;

Fig. 3 is an enlarged perspective view of the left end of the coil shownin Fig. 1 illustrating the coil before it is completely wound, and theimproved insulator applied thereto;

Fig. 4 is an enlarged plan view of the insulator before being applied tothe coil, and

Fig. 5 is an enlarged vertical section taken on the line 5-5 of Fig. 4.

Referring now to the drawing, Figs. 1 and 2, one embodiment of anelectrical coil embodying the features of the invention is shown in theform of a spool wound electrical coil ill of the type used'extensivelyfor relays and other electrical apparatus. The coil l0 comprises a spoolhaving a core i2, usually made of a soft magnetic metal or alloy and aspool head I! or flange, generally made of fibre or other non-conductingmaterial rigidly secured at each end of the core.

To eflfectively insulate the metal core l2 from the subsequently appliedwinding the section of the core between the heads I3 is covered with asheet ll of cellulose acetate or other material having satisfactorydielectric properties. A split disk or washer i5 (Fig. 2) preferablymade of cellulose acetate is placed around the core I! and abuttedagainst the inner face of each spool head l3. The washer I! has acentral particularly aperture conforming with the contour of theinsulating sheet I! surrounding the core and a from the inner face ofthe flange I6 extending end of the lead wire 7 the core for washer andover the core insulating sheet II for a short distance.

Preparatory to the winding of the coil lo a suitable length of barestranded terminal or lead wire I9 is connected at its inner end to theuninsulated inner end of enameled insulated winding wire 20, by eithersoldering the ends together or in any suitable manner, as indicated at2|. The outer end of the stranded lead wire I9 is then passed throughaperture 22 formed in the head l3 andwasher l5 adjacent the periphery ofthe core l2. Thereafter, the inner I9 is spirally wrapped around a fewturns, as shown at 23 (Figs. 2 and 3), and a second split disk or washer23 of suitable insulating material and provided with a central aperture21 adapted to freely surround the stranded lead wire turns 23 is placedon the core and pressed toward the spool head l3 and washer l5, thelength of the lead wire l9 between th'eaperture 22 of the washer l5 andthe core being held between the opposed faces of the two washers.

'Before the actual winding of the coil a member of insulating materialis wound around the few turns 23 of the stranded bare lead wire I! andits connection 2| to the winding wire 23 'to prevent,'as hereinbeforedescribed, the subsequently wound adjacent layers of enameled windingwire from working or being pressed downwardly into contact with the barelead wire with the possibility of short circuiting one or 7 more layersof the coil.

One form of an interleaving insulator 30 by the use of which the abovedifilculty is overcome is shown in detail in Figs. 4 and 5. Thisapplying the insulator 30 sheet material of insulator is preferablymade'from cellulose acetate or a similar non-fibrous material havingsatisfactory dielectric properties. .In producin the insulator 30 asheet of cellulose acetate strip material of a suitable width and whichis relatively thin is formed with a longitudinally extending flat doublefold as indicated at 3|, the longitudinal edges of the fold beingparallel vto and spaced-from the corresponding edges of the sheet. Theseveral thicknesses of material comprising the flat fold 3| arecoalesced by first forming a series of perforations 32 in two adjacentlayers thereof, thelperforations extending longitudinally along andintermediate opposite edges of the fold and thereafter applying acetoneto the perforations by suitable means, for instance, by drawing afountain pen therealong. The acetone seeps through the perforations andbetween the layers of folded material and firmly secures the severallayers together. In the present embodiment colored acetone is preferablyused which produces a colored line 33 of appreciable width along thelength of the fold 3| for a purpose which will be presently referred to.An edge portion 34 of the sheet extending from one edge thereof to theadjacent edge of the fold 3| is relatively narrow as compared to an edgeportion 35 extending from the opposite edge of the fold to thecorresponding edge of the sheet. Formed in and along the length of thenarrow' edge portion 34 are a series of serrations 31 i which extendfrom the outside edge of the portion to substantially the adjacent edgeof the fold 3|. I

The insulator 30 is applied to the connected lead and winding wires l9.and, respectively, by placing the serrated edge portion 34 at theannular corner or juncture of the inner face of the washer 26 and theinsulated core l2 and wrapping it around the connected wires, theinsulator being of such a length that several thicknesses thereof may beapplied. The fold is placed at the annular corner or juncture of theinner face of the coil head washer 23 and the core cover l4, thusproviding increased insulation at this point. Due to the serrations 31and the single thickness of material extending from the outer edge ofthe portion 34 to the adjacent edge of the fold 3| the edge portion 34will readily flex adjacent the edge of the fold and form an outwardlydirected flange lying closely against the face of the head washer 26.

The colored .line 33 hereinbefore described, along 4 I the fold 3| isvery useful to an operatordn since the line, which is relatively closeto the serrated edge portion 34, readily indicates which edge portion isserrated and thus in picking an insulator from a supply and carrying itto the coil being wound it will.

be clearly apparent to the operator which edge portion is to be placedagainst the washer 23. The edge portion 35 is of such width that it willcompletely form an insulating cover for the several turns of uninsulatedlead wire l9 audits connection 2| to the winding wire 20.

Due to the thinness which the insulator is made, it would be easilytearable, particularly at its serrated edge portion 34, during thehandling thereof in applying it to the coil, if not reinforced by thefold 3| which effectively prevents tearing thereof. Furthermore, thefold 3| serves to stiffen the insulator, thus making it easier to handleand apply, and also provides increased insulation at the annular cornerof the head and core.

The winding of the coil is then continued in the usual manner and theouter end of the winding wire 20 connected to a stranded terminal orlead wire 40 and a few turns of the lead wire and connected winding wireare taken around the body of the coiled wire, the turns of wire beingenclosed in a suitable insulator 4|. Thereafter, the outer end of thelead wire 40 is threaded through apertures in the washers 28 .and I5 andthe head I3 and an outer insulating cover 42 is applied.

It will be understood that the nature and embodiment of the inventionherein described is merely illustrative and that many changes andmodifications may be made therein without departing from the spirit andscope of the invention as defined in the appended claims.

What is claimed is:

1. An'electric coil comprising a core with a head, an insulated windingon said core, a lead connected at itsinner end to said winding adjacentthe inner face of the head and extending outwardly thereof, and aninsulator element covering the connection of said lead wire to saidwinding and extending outwardly at the annular corner of the inner faceof the head and surrounding said core, said insulator comprising a sheetof non-fibrous insulating material having a fold spaced from an edgeportionfor preventing tearing of the sheet pastthe fold, said edgeportion adapted to readily flex outwardly from an edge of the foldduring the application of the insulator to the coil, said fold edgebeing applied at said annular corner.

2. An electrical coil comp ing a core with a of the cellulose acetateoutwardly thereof, and an insulator element covering the connection ofsaid lead wire to said ering the connection of said lead wire to saidwinding and extending outwardly at the annular winding and extendingoutwardly at the annular corner of the inner face of the head and saidcorner of the inner face of the head and surcore, said insulatorcomprising a sheet of cellurounding said core, said insulator comprisinga 5 lose acetate material having a flat fold spaced sheet of non-fibrousinsulating material having a from an edge of the sheet, said foldpreventing fold extending along an edge portion of the sheet tearing ofthe sheet past the fold, the edge of the with the folded materialsecured together, said sheet having a series of serrations extendingfold preventing tearing of the sheet past the toward the fold forpermitting the edge portion fold, said edge portion adapted to readilyflex to readily flex adjacent an edge of the fold duroutwardly from anedge of the fold during the ing the application of the insulator, saidfold beapplication of the insulator to the coil, said fold ing appliedat said annular corner. edge being applied to said annular corner. 6. Anelectric coil comprising a core with a 3. An electric coil comprising acore with a head, an insulated winding on said core, a lead head, aninsulated winding on said core, a lead connected at its inner end tosaid winding adconnected at its inner end to said winding adjacent theinner face of the head and extending jacent the inner face of the headand extending outwardly thereof, and an insulator element covoutwardlythereof, and an insulator element ering the connection of said lead wireto said covering the connection of said lead wire to said winding andextending outwardly atthe annular winding and extending outwardly at theannular 2o corner of the inner face of the head and said corner of theinner face of the head and said core, said insulator comprising a sheetof cellucore, said insulator comprising a sheet .of nonlose acetatematerial having a double fold of fibrous insulating material having afold extendthree thicknesses of material extending longiinglongitudinally thereof and spaced from an tudinally thereof and spacedfrom an edge 'of edge of the sheet for preventing tearing of the 5 thesheet, two adjacent thicknesses of material sheet past the fold, saidedge of the sheet having of the fold having a series of perforations,and a series of serrations extending toward the fold acetone within saidperforations for coalescing for permitting the edge portion to readilyflex the three thicknesses of folded material, said outwardly from anedge of the fold during the fold preventing tearing of the material pastthe application of the insulator to the coil, said fold fold, said edgeportion adapted to readily flex edge being applied at said annularcorner. outwardly from an edge of the fold during the 4. An electriccoil comprising a core with a application of the insulator to the coil,said fold head, an insulated winding on said core, a lead edge beingapplied at said annular corner. connected at its inner end to saidwinding ad- 7. An electric coil comprising a core with a Jacent theinner face of the head and extending head, an insulated winding on saidcore, a lead outwardly thereof, and an insulator element connected atits inner end to said winding adcovering the connection of said leadwire to said jacent the inner face of the head and extending winding andextending outwardly at the annular outwardly thereof, and an insulatorelement covcorner of the inner face of the head and said ering theconnection of said lead wire to said core, said insulator comprising asheet of celluwinding and extending outwardly at the annular loseacetate material having a fold extending corner of the inner face of thehead and said longitudinally thereof and spaced from an edge core, saidinsulator comprising a sheet of celluof the sheet, several thicknessesof materialpf lose acetate material having a flat double fold the foldhaving a series of perforations, and aceof three thicknesses of materialspaced from an tone within said perforations for coalescing the edge ofthe sheet, two adjacent thicknesses of folded material, said foldpreventing tearing of material of the fold having a series of perforathematerial past the fold, said edge portion tions, and acetone within saidperforations efadapted to readily flex outwardly from an edge fective tocoalesce the three thicknesses of maof the fold during the applicationof the insulaterial, said edge of the sheet having a series of tor tothe coil, said fold edge being applied at 5 parallel serrationsextending toward the fold for said annular corner. permitting the edgeportion to readily flex adja- 5. An electric coil comprising a core witha cent an edge of the fold during the application head, an insulatedwinding on said core, a lead of the insulator to the coil, said foldedge being connected at its inner end to said winding adapplied at saidannular corner. jacent the inner face of the head and extendingoutwardly'thereof, and an insulator element cov- CHARLES W. VERRILL.

